The present invention is intended for use in connection with digital user units, preferably in the form of digital pens, which are capable of detecting positions on the basis of a position-coding pattern. If a user writes with such a pen on a base which is provided with the correct type of position-coding pattern, a sequence of positions is recorded, which constitutes a “digital copy” of the handwritten information written on the base.
Such a digital device can, by means of a short range radio link (such as a BLUETOOTH link), communicate with a computer system, for instance a personal computer (PC). This enables storing in the computer system of “digital copies” of the above type. Moreover such a connection allows interaction between the digital device and applications in the computer system. In addition to storing handwritten information, the user can by means of the user unit activate other functionalities in such applications.
For example, the user can, by marking with the user unit a certain area on a sheet of paper and thus detecting certain predetermined positions, initiate a function in an application in the computer system. Examples of such functions can be to process previously recorded handwritten information in a certain manner, send such information to a certain recipient etc. Thus, this affords the attractive possibility of using the user unit and a position-coded sheet (pen and paper) as a user interface for an application in a computer system.
In this context, there is a pronounced interest in letting the user unit interact also with other applications than those operating in precisely the computer system with which the user unit is in direct connection. For instance, a payment transaction, which a user initiates by filling in a position-coded form, may have to be recorded and checked in a central server unit belonging to a bank where the user is a customer.
There may thus be a need to establish connections between the user unit and computer resources, such as a server connected to the same LAN (Local Area Network) as the computer system or a server connected to the Internet. This could be carried out by using the computer system (PC) as a link between the user unit and these computer resources.
A first conceivable approach of achieving this is to let the computer system function as a client in relation to the desired computer resources. In such cases, the computer system (PC) initiates all communication with the various computer resources. The user unit (pen) contributes position information which causes client software in the computer system to act in a certain manner. In this case it may be said that the system acts “intelligently” since this is where position information is converted into functionality.
A drawback of such an approach is the difficulty of guaranteeing secrecy for the user who does not necessarily own and control the computer system (PC). For example, in safe transactions it is desirable to maintain transmitted information encrypted all the way between the pen and the computer resource used. Such an approach also makes it difficult to use the user unit offline, i.e. without direct contact with the computer system, and carry out recorded transactions on a later occasion when a contact has been established.
A second conceivable approach is to let the user unit function as a client and have the possibility of establishing on its own a packet switched connection with the required computer resource. The user unit can then on its own generate and receive data packets according to the TCP/IP protocols, which packets are only transmitted by the computer system to which the user unit is connected.
For a plurality of technical reasons, this second approach is difficult to accomplish. In most operating systems for personal computers, it is difficult to handle a plurality of TCP/IP transactions at the same time. Moreover it is complicated to allocate a (required) IP address from the computer system to the user unit. It may also be the case that the computer system acts behind a firewall and has proxy settings which are difficult for the user unit to access and without which no connection can be established. Similarly, it is difficult for the user unit to carry out DNS (Domain Name System) calls.